|Traditional Medicinal Plants (Dar Es Salaam University Press - Ministry of Health - Tanzania, 1991, 391 p.)|
|PART I: USE AND PROMOTION OF TRADITIONAL MEDICINAL PLANTS IN THE AFRICAN REGION|
E. N. MSHIU
Traditional Medicine Research Unit
P.O. Box 65001
Dar es Salaam
Tie paper reviews issues on biotechnology, and medicinal plants. Third World countries do not have mechanisms for safeguarding sovereignty over their genetic resources, or foe the conservation of tropical products and the traditional knowledge of indigenous people. Advances in biotechnology have heightened interest among biotechnological and pharmaceutical companies in herbal plants and microbiological organisms of the South, as a source of raw materials for new pharmaceutical products. Third world countries must also benefit from their knowledge and biological treasures. Long term conservation measures of their plant resources must thus be put in place. In the process, the indigenous people who enrich the scientists with a wealth of information on traditional medicinal uses of the plants, must be treated with respect, and be given the recognition they deserve.
With advances in biotechnology there is renewed and increased interest in the vascular and other plants of the South as a source of raw materials for developing new pharmaceutical products. At least 7000 medical drug compounds in modern Western pharmacopeia are derived from plants. In 1985 the retail value of plant-derived drugs in the industrialized world was estimated to be at least $43 million. In recent decades, pharmaceutical companies have focused on the synthetic production of medicinal products, but the chemists have found it difficult to improve on what nature has provided. In fact, of all the useful plant-derived drugs, only 10 are synthesized in the laboratory. The rest are still extracted from plants.
With advances in plant molecular biology, new cell culture techniques, new bio-assays, and the availability of new and precise analytical methods for screening the plants, discovery of natural products is expanding. A 1988 consultancy report by a United Kingdom firm, Mc Alpine and Warrier, indicated that the market potential for sophisticated herbal drugs in the Western World could range from $4.9 billion to $47 billion by the year 2000, if the AIDS epidemic continued unchecked.
The world's tropical moist forests cover 6% of the earth's surface, and contain at least 50% of all the vascular plant species. It should be noted that, 65 - 75% of higher plant species are indigenous to the rain forests. Little is known about the vast majority of these species, and, because of deforestation, they are becoming extinct at a rate unparalleled in human history. Yet, the rain-forests plants have been considered to be a complex chemical storehouse for modern medicine (Principe, 1989).
The world picture
Less than 1% of tropical forest species have been examined for their possible use to human kind. But at least 1400 plant species of tropical forests are believed to be of potential in curing cancer. It is noted with concern that with tropical forests being destroyed at the rate of up to 100 acres per minute, and the global rate of species extinction now estimated at 400 times faster than in the recent geological past, scientists warn that 20 - 25% of the world's vascular plant species will be lost by the year 2000 (RAFI, 1989).
It is difficult to put a price tag on medicinal plant species, but it helps to consider the enormous social and economic value of a few of our tropical medicinal plant "superstars".
The first example, Madagascar's rosy periwinkle plant (Catharanthus roseus) is a source of at least 60 alkaloids, of which the two important alkaloids, vincristine and vinblastine, have revolutionized the treatment of childhood leukemia and hodgkin's disease. One requires 15 tonnes of the plant leaves to make one ounce of vincristine, which sells for US 9100,000 a pound. Commercial sales of drugs derived from rosy periwinkle total approximately $160 million per year.
The second example is Rauvolfia. Material obtained from the plant, the so-called, "shake root" plant, from monsoon forests in India, contains an alkaloid, reserpine, which forms the base of tranquilizer products, and other drugs used in the treatment of hypertension and schizophrenia. In the early 1980s the retail sales of reserpine-based products in the U.S.A. alone, exceeded $280 million a year. Biotechnological companies and Pharmaceutical Corporations are combing the tropical forests of the Third World countries, in pursuit of exotic medicinal plants as they are interested in natural products screening (RAFI, 1989).
It is reported that, the Japanese and European companies are even more active than the United States counterparts. Few of them are doing their own collections in tropical forests, and some are contracting with third party collectors. For example, Merck Sharpe and Dohme from United States, a leader in natural products discovery, routinely makes contracts for the collection of tropical plants. The company is now in Brazil, searching for a medicinal plant superstar, tiki uba, which has uses as an anti- coagulant. Some of the companies have turned to China, where herbal remedies have been used for centuries. It is reported, for example, that a United State drug company, Up John, is studying ten compounds from the ancient Chinese herbal medicines, with the aim of developing new drugs to fight cancer, cardiovascular diseases, and disorders of the central nervous system. G.D. Searle and Company, is evaluating extracts from Chinese plants used for gastro-intestinal disorders.
It is further reported that the Biotics Company from the United Kingdom started working with the European Commission in 1986 as a commercial broker to supply exotic plants from developing nations, for pharmaceutical screening. Major pharmaceutical companies, such as ICI, Beechams, Rhone Paulen, Glaxo, Hoechst, Novo and Sandoz, expressed interest in obtaining extracts from indigenous plant species from the Third World. According to information available, Biotics Limited, for example, provided Glaxo Pharmaceuticals (UK) with plants from Ghana.
Medicinal substances extracted from vascular and other plants from the South today will become the patented products of biotechnology of tomorrow. The potential for developing new drugs, which may hold promise for curing diseases such as cancer and other life threatening ailments, is great. Despite the potential benefits, there is a historic disregard for Third World cultures from which these plants are extracted.
The discovery of medicinal substances from vascular plants does not just happen by accident. The people who have traditionally lived in tropical forests are the key people to assist the modern scientists in the understanding, utilization and conservation of tropical plant diversity.
Professor Norman Farnsworth of the University of Chicago, U.S.A., estimates that three quarters of all plant-derived drugs were discovered because of their prior use in indigenous medicine. Mark Plotkin of the World Wildlife Fund, observes that "...because you have a Ph.D. and the other guy can't read, it does not mean you know more about botany than he does". He gives the example that forest dwelling Indians employ at least 1,300 plant species for medicine and related purposes.
Worldwide, Third World communities use at least 3000 plant species to control fertility. According to Plotkin, every time one medicineman dies, it is as if a library was burned down. He goes on saying that it is worse than that, because if a library is burned, most of the information can be found in other libraries. However, when a medicineman dies his knowledge is lost, and is lost forever!
The most efficient way to identify plants, and their medicinal properties, is to ask the people who use them (Plotkin 1988). Most healers, in our experience, have no written records of the plants they use.
It should be further added that the demand for the Souths exotic germ plasm is not limited to plants only, nor is collecting restricted to tropical forests and land surfaces. There is also interest in bacteria, algae, fungi and protozoa, and a wide range of marine organisms. These also have potential as sources of valuable pharmaceutical raw materials. For example, Mycosearch, a small biotechnology company in the USA collects fungi samples from around the world, and screens them for valuable natural compounds. The company maintains a collection of over 20,000 fungi, and over 50% of them originate from the tropics. Pharmaceutical companies such as Hoffman La Roche, Dupont, Ciba Geigy, Schering Plough, and others, pay hundreds of dollars per sample for potentially valuable fungi.
Companies such as Smith Kline and French, and the National Cancer Institute (USA), are involved in collecting from tropical waters, corals, sponges, anenomes and other organisms. Sea Pharm, a marine pharmaceutical company from the USA, has a $3.6 million contract with NCI, to collect in tropical seas and elsewhere. Scientists believed that organisms were not capable of growing more than 30 metres below ground but the recent discovery of subsurface microbial collections, located 600 metres below the earth's surface, has uncovered a potentially vast and new frontier for discovering living organisms that may be a future source of pharmaceuticals.
The conservation and utilization of medicinal plants is socially and economically important for our developing nations. WHO estimates that 80% of the World's population depend on traditional herbal medicine. Indeed, herbal medicines offer tremendous economic potential, not only as an export crop, but - the resources for developing locally controlled industry, which can substitute the costly pharmaceutical imports. Such developments are taking place in Thailand, Turkey, the Philippines, and in China, where herbal medicines constitute a big business.
In conclusion, Third World countries should not be the loser in the frantic search by biotechnology and pharmaceutical transnationals in the tropical forests. Our vascular plants in the forests are the raw materials for new drugs and for genetic seed improvement. Plants which can withstand hostile environments, which resist attack by the common pests, or which give more and better fruits are the material of a US 116 billion world seed market.
In 1985, industrialized countries paid at least US $43 billion for plant-derived drugs. Indeed, developing countries get nothing for the plants collected by the gene hunters, on behalf of powerful companies. At least they should pay royalties for the products developed from them (Shand, 1989). Furthermore, industrialized countries have now recognized that the useful properties of the Souths plants are the result of centuries of a careful selection by many generations of peasants, but they are resisting the logical conclusion that developing countries should be compensated for their traditional knowledge and biological storehouse.
The search for new medicinal plants is a race against time. Tropical forests of the Third World hold an incalculable value, as an untapped emporium of germplasm for the development of new drugs. The most powerful scenario is that pharmaceutical and biotechnological interests will become powerful allies in an effort to stop or curtail the destruction of the world's tropical forests. Third World countries and indigenous people should also benefit from their knowledge and biological treasures. Long term conservation measures must be put in place. In the process of collecting the plants, the indigenous people must be treated with respect, and be given the recognition they deserve. Procedures should be developed to compensate the healers and others for the utilization of their knowledge and their biological resources. Here is where we require the cooperation of the Third World countries, for a common plan of action.
Lastly, despite the many constraints which exist in developing countries, such as lack of skilled or trained manpower, lack of technical know-how and financial resources, and shortage of equipment, frequent exchanges of ideas and experience among scientists and technologists should be encouraged and financed, so as to lead to self-reliance, in the various aspects of research and development in the proper utilization and judicious exploitation of herbs, as a natural resource. It is noted that, in developing countries, there are no substitutes for herbal drugs in terms of both cost and availability of raw materials. Hence the technology involved elsewhere, in the revival and use of herbal-based medicines, should be made available to the developing countries for the better use of their natural resources. In this respect, the role of some of the United Nations Organizations such as UNDP, UNESCO, UNIDO, FAO and WHO is vital, in providing necessary assistance in various aspects of research and development, and in improving the efficiency and capability of the local scientists.
McAlpine, P. and Warrier, K. (1989). Rural Advancement Fund, International Communique, March 1989.
Plotkin, M.J. (1988). The Economist, April 2.
Principe, P. 1989. The economic value of biological diversity among medicinal plants. OECD Environmental Monograph. Organisation for Economic Cooperation and Development. Paris.
RAFI (1989). Biotechnology and medicinal plants, March 1989.